Radiocarbon chronology of occupation of the site Chicha and Bayesian statistics for the assessment of a discontinuous transition from Late Bronze to Early Iron Age (West Siberia)

The Late Bronze to Iron Age transition in West Siberia involved significant cultural and political changes, which were reflected in the emergence of protourban settlements in the forest-steppe zone. The transition is roughly dated to the turn from the 2nd to the 1st mil. BC, mainly based on archaeological artefacts and on the general sociocultural development. A more precise radiocarbon dating for this transition was problematic mainly because of the general lack of data for West Siberia. This paper analyzes the chronology of the Late Bronze to Iron Age transition at Chicha, a reference site in the region for this period. The assessment of a possible hiatus between the Late Bronze Age and the following transitional period at Chicha is the key issue of our paper, as its presence may have far reaching cultural implications. To increase the precision of the radiocarbon chronology with focus on the possible hiatus, the samples from well-defined stratigraphic contexts were analyzed using Bayesian modeling incorporating stratigraphic information. The performed chronological modeling supports existing archaeological hypothesis of a hiatus at the very end of the 2nd mil. BC, just before the regular emergence of a new protourban settlement at the site of an abandoned Late Bronze settlement. A sensitivity analysis including the simulated hiatus confirms the reliability of the model. A complete population change seems to be plausible. The protourban settlement of Chicha, typical of the Transitional period, did not exist very long. With the emergence of the early nomadic cultures in the South Siberian steppes at the beginning of the 1st mil. BC, it most probably stopped functioning. The cultural development of that time, former believed to be continuous, was deeply interrupted several times.